It is well known for lubricating oils to contain a number of surface active additives (including antiwear agents, dispersants, or detergents) used to protect internal combustion engines from corrosion, wear, soot deposits, sludge deposits, and acid build up. Often, such surface active additives can have harmful effects on engine component wear (in both iron and aluminium based components), bearing corrosion or fuel economy. A common antiwear additive for engine lubricating oils is zinc dialkyldithiophosphate (ZDDP). It is believed that ZDDP antiwear additives protect the engine by forming a protective film on metal surfaces. ZDDP may also have a detrimental impact on fuel economy and efficiency and copper corrosion. Consequently, engine lubricants may also contain a friction modifier to obviate the detrimental impact of ZDDP on fuel economy and corrosion inhibitors to obviate the detrimental impact of ZDDP on copper corrosion. Friction modifiers and other additives may also increase lead corrosion.
Further, engine lubricants containing phosphorus and sulphur compounds such as ZDDP have been shown to contribute in part to particulate emissions and emissions of other pollutants. In addition, sulphur and phosphorus tend to poison the catalysts used in catalytic converters, resulting in a reduction in performance of said catalysts.
There has been a commercial trend for reduction in emissions (typically reduction of NOx formation, SOx formation) and a reduction in sulphated ash in engine oil lubricants. Consequently, the amounts of phosphorus-containing antiwear agents such as ZDDP, overbased detergents such as calcium or magnesium sulphonates and phenates have been reduced. As a consequence, ashless additives have been contemplated to provide friction or antiwear performance. It is known that surface active ashless compounds such as ashless friction modifiers may in some instances increase corrosion of metal, namely, copper or lead. Copper and lead corrosion may be from bearings and other metal engine components derived from alloys using copper or lead.
U.S. Pat. No. 3,933,662 (Lowe, published 20 Jan. 1976) discloses mono-ester polyalkoxylated compounds combined with alkaline earth metal carbonates dispersed in a hydrocarbon medium to provide lubricating compositions of superior acid neutralizing capability and rust inhibition in internal combustion engines. The internal combustion engine was tested using a Sequence IIB engine test. The Sequence IIB engine test evaluates valve guide rust and pitting.
U.S. Pat. No. 4,305,835 (Barber et al, published 15 Dec. 1981) discloses lubricating oil composition for use in the crankcase of an internal combustion engine, having improved resistance to the formation of emulsion-sludge in the area under the engine rocker cover, which contains the combination of an oxyalkylated alkylphenol-formaldehyde condensation product and an oxyalkylated trimethylolalkane.
U.S. Pat. No. 4,402,845 (Zoleski et al., published 6 Sep. 1983) discloses improved spreadability of marine diesel cylinder oils by the incorporation therein of a polyethylene glycol of the formula: R—CH2O—(CH2CH2O)nH wherein n ranges from 7 to 40 and R is an alkyl group containing from 11 to 15 carbon atoms.
U.S. Pat. No. 4,438,005 (Zoleski et al., published 20 Mar. 1984) discloses improved spreadability of marine diesel engine cylinder lubricants by the incorporation therein of a spreadability improving amount of at least one polyoxyethylene ester of the formula: wherein n ranges from 18 to 22 and R is an alkyl group having 11 to 17 carbon atoms in the chain.
U.S. Pat. No. 4,479,882 (Zoleski et al., published 30 Oct. 1984) discloses improved spreadability of marine diesel cylinder oils by the incorporation therein of a spreadability improving amount of a polyalkoxylated phenoxy compound having the formula: wherein R is an aliphatic hydrocarbyl group having from 5 to 70 carbon atoms and n ranges from 14 to 30.
U.S. Pat. No. 4,493,776 (Rhodes, published 15 Jan. 1985) discloses a lubricating composition with improved rust and corrosion inhibition comprising an additive that is a combination of (A) R1O[C2H4O]xH and/or R2O[C3H6O]yH with (B) R3O[C2H4O]x[C3H6O]yH and/or R4O[C3H6O]y[C2H4O]xH, wherein R1, R2, R3 and R4 are hydrocarbyl radicals selected from alkyl, aryl, alkaryl, and arylalkyl groups or combinations thereof having from about 10 to about 24 carbon atoms; and wherein x and y may vary independently in the range from 3 to about 15. The additives are hydroxyl-terminated.
U.S. Pat. No. 4,973,414 (Nerger et al., published 27 Nov. 1990) discloses monofunctional polyethers having hydroxyl groups contain, as built-in terminal groups or monomers, (a) 1 to 30% by weight of one or more C4- to C24-alkylmonophenols, (b) 1 to 30% by weight of one or more C8- to C24-monoalkanols, (c) 1 to 30% by weight of one or more C10- to C20-1,2-epoxyalkanes and (d) 45 to 80% by weight of propylene oxide or a lower alkylene oxide mixture consisting mainly of propylene oxide the sum of components (a) to (d) adding up to 100% by weight, and have average molecular weights of 600 to 2,500.
U.S. Pat. No. 5,397,486 (Small, published 14 Mar. 1995) discloses a method for inhibiting wear of silver wrist-pin bearings in a two-cycle railroad diesel engine which method comprises lubricating the internal portion thereof with a lubricating oil composition consisting essentially of: a single or multi-grade oil of lubricating viscosity; a sufficient amount of a calcium overbased sulfurized alkylphenate composition so that the total base number in the lubricating oil composition is from about 5 to about 30; and a wear-inhibiting amount of at least one lubricating oil soluble and compatible compound based upon a hydroxy-terminated polyether having 2 to 6 carbon atoms.
Polyalkoxylated compounds are also disclosed in U.S. Pat. No. 2,681,315 (Tongberg, published 15 Jun. 1954) and U.S. Pat. No. 2,833,717 (Whitacre, published 6 May 1958) teaching lubricating oil compositions containing poly(oxyethylene)alkylphenols useful as rust or corrosion-inhibiting additives.
U.S. Pat. No. 2,921,027 (Brennan 12 Jan. 1960) teaches poly(oxyethylene)sorbitan fatty acid ester as a rust inhibitor.
1,2-poly(oxyalkylene)glycol lubricating compositions are disclosed in U.S. Pat. No. 2,620,302 (Harle, published 2 Dec. 1952), U.S. Pat. No. 2,620,304 (Stewart et al., published 2 Dec. 1952), and U.S. Pat. No. 2,620,305 (Stewart et al., published 2 Dec. 1952).